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Add x86-64-v2, x86-64-v3, and x86-64-v4 as available target_cpus #82024

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hsivonen opened this issue Feb 12, 2021 · 7 comments
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Add x86-64-v2, x86-64-v3, and x86-64-v4 as available target_cpus #82024

hsivonen opened this issue Feb 12, 2021 · 7 comments
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A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. C-feature-request Category: A feature request, i.e: not implemented / a PR. O-x86_64 Target: x86-64 processors (like x86_64-*) T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@hsivonen
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hsivonen commented Feb 12, 2021 •
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Page 14 of the 2020-08-31 version of the AMD64 supplement to the System V ABI defines new microarchitecture levels that bundle instruction set extensions: x86-64-v2, x86-64-v3, and x86-64-v4. According to a Red Hat blog post, LLVM 12 will support these.

rustc should support these as target_cpu values, enable the right target_features, and pass them appropriately to LLVM.

Internals thread
@jonas-schievink jonas-schievink added A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. C-feature-request Category: A feature request, i.e: not implemented / a PR. O-x86_64 Target: x86-64 processors (like x86_64-*) T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Feb 12, 2021
@IsaacWoods
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The link to the internals thread also points to RedHat's blog. I'm guessing this is the internals thread.

@hsivonen
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Oops. Updated the link. Thanks.

@ojeda
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ojeda commented Feb 12, 2021

rustc does not manage these options, LLVM does. Thus when we move to LLVM 12, we will get these.

@est31
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est31 commented Feb 12, 2021

LLVM commit for reference: llvm/llvm-project@012dd42e027e

@est31
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est31 commented Feb 12, 2021

Also I confirm what @ojeda said. In #79043, all I had to do was patch LLVM to add availability of these target_cpus. No changes in rustc were neccessary.

@vDorst vDorst mentioned this issue Mar 23, 2021
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@jyn514
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jyn514 commented Jun 25, 2021

The compiler is now using LLVM 12.0.1, so this might be fixed?

@hsivonen
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hsivonen commented Jul 5, 2021

Indeed, this is now fixed. Thanks.

@hsivonen hsivonen closed this as completed Jul 5, 2021
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A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. C-feature-request Category: A feature request, i.e: not implemented / a PR. O-x86_64 Target: x86-64 processors (like x86_64-*) T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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@hsivonen @ojeda @jonas-schievink @est31 @IsaacWoods @jyn514